1. Field of the Invention
The present invention relates to scroll compressors, and in particular to scroll compressors known as xe2x80x9cdouble rotational compressors,xe2x80x9d in which a drive scroll rotates in synchronism with a driven scroll about respective rotational axes that are offset to each other.
2. Description of Related Art
Japanese Laid-open Patent Publication No. 7-229480 discloses a double rotational scroll compressor, in which a drive scroll and a driven scroll oppose each other and define a compression chamber therebetween. The drive scroll is secured to a rotor of an electric motor, and the rotor and the drive scroll are rotatably and coaxially supported within a housing. The driven scroll is rotatably supported by an eccentric mechanism that is mounted on a shaft and the shaft extends though the rotor. An Oldham""s coupling serves to transmit the rotation of the rotor or the drive scroll to the driven scroll.
In such a scroll compressor, the rotor and the drive scroll secured to the rotor oppose each other and the driven scroll is interposed therebetween. Further, respective support shafts must support the rotor and the drive scroll. Therefore, the drive scroll is actually supported by support shafts disposed on both sides. In other words, the support shafts mounted within the housing must rotatably support the rotor of the electric motor. As a result, the length of the compressor along the axial direction of the rotor is relatively long. In addition, because the driven scroll is mounted on the support shaft (which supports the rotor) by means of the eccentric mechanism, the number of parts and the manufacturing costs of the compressor are relatively high.
Therefore, one object of the present teachings is to provide improved scroll compressors that preferably are more compact than known scroll compressors. Such scroll compressors may, e.g., find advantageous application in vehicle air conditioning systems.
In one aspect of the present teachings, scroll compressors are taught that have a drive scroll opposing a driven scroll. One or more compression chambers may be defined between the drive scroll and the driven scroll. One or both of the drive scroll and the driven scroll may be supported in a cantilever manner. Therefore, it is possible to eliminate a rotor support mechanism (a shaft and a bearing) as compared to known scroll compressors. Further, the length of the compressor along the axial direction of the scrolls can be reduced as compared to known scroll compressors. Therefore, scroll compressors according to the present teachings may be relatively compact in size. In addition, it is possible to eliminate some parts of the eccentric mechanism that are required in known scroll compressors, thereby reducing manufacturing costs.
In another aspect of the present teachings, a plane bearing or a needle bearing may movably support at least one of the drive scroll or the driven scroll along the axial direction. In addition, a refrigerant (cooling medium) may be compressed within the compression chamber and then may be discharged to the side of the drive scroll or the driven scroll that is movably supported along the axial direction. Therefore, the pressurized or compressed refrigerant may apply a force to the rear side of one of the drive scroll or the driven scroll. The amount of force applied to the rear side of the drive scroll or the driven scroll can be selectively determined by adjusting the size of a discharge chamber that may be defined within the drive scroll or the driven scroll. That is, the area of the rear side of the corresponding scroll, to which area the discharge pressure is applied, may be selectively modified in order to adjust the amount of force applied by the pressurized refrigerant. Therefore, the contacting pressure between the drive scroll and the driven scroll can be appropriately determined.
In another aspect of the present teachings, a transmission or other means for rotating the drive scroll in synchronism with the driven scroll may be provided. For example, the transmission may include a first torque transmission member disposed on the drive scroll and a second torque transmission member disposed on the driven scroll. The first torque transmission member may slidably contact the second torque transmission member, so that the rotation of the drive scroll is transmitted to the driven scroll. Therefore, the driven scroll can synchronously rotate with the drive scroll and the rotational axis of the driven scroll is preferably offset to the rotational axis of the drive scroll.
Preferably, the first transmission member can rotate relative to and around the second torque transmission member. Further, the radius of rotation of the first transmission member may be equal to the distance between the rotational axes of the drive scroll and the driven scroll. Therefore, rotational torque may be smoothly transmitted.
In another aspect of the present teachings, the first transmission member may comprise one of a pin or a ring and the second transmission member may comprise the other of a pin or a ring. In that case, the pin can slidably rotate along the inner circumferential surface of the ring. In another aspect, the first transmission member and the second transmission member may comprise respective pins and a ring may couple the respective pins. In that case, the pins can slidably rotate along the inner circumferential surface of the ring. In another aspect, the first and second torque transmission members may respectively comprise a first pin and a second pin. In that case, the first pin can slidably contact and rotate around the second pin. Further, a ring may be rotatably mounted on one of the first pin or the second pin, so that the first pin or the second pin can slidably rotate around the ring.
Additional objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.